Along with practical application of a lower-inertial high-power AC servomotor (hereinafter, abbreviated as “servomotor”) capable of outputting fluctuating torque in high frequency over 100 Hz, a servomotor-typed mechanical testing device (e.g., a fatigue testing device and a vibration testing device) using a servomotor as a driving source in place of a conventional hydraulic actuator has been commonly accepted. While the servomotor is relatively small and is easier to be handled and maintained compared to a hydraulic device, demands for the mechanical testing device, which enables advanced tests using a plurality of servomotors, have been increased. In the meantime, the servomotor may contain problems such that controlling synchronously the plurality of servomotors, of which output fluctuates in high speed, requires advanced controlling techniques, and a large amount of development costs and a long term of developing time are required to develop dedicated controlling programs.
Developer's environments to effectively build a controlling system to synchronously control a plurality of servomotors are provided by manufacturers of servomotors (non-patent document 1: Mitsubishi Integrated FA Software MELSOFT, effective May 2005, pages 25-26. [online] MITSUBISHI ELECTRIC. [retrieved on Nov. 2, 2011]. Retrieved from the Internet). Non-patent 1 discloses a visual programming language called mechanical system program. The mechanical system program simulates hardware-based synchronous control to mechanically control driving of a plurality of output shafts synchronously by use of mechanical elements, such as gears and cams, on software basis and synchronously control the plurality of servomotors associated with output shafts (virtual shafts) on the software basis.